Build a 2-wheel Cargo Bike

as promised in my last instructable, here's my attempt to build a 2-wheeler. why? i got infected by the bike-building virus. especially cargo bikes are just awesome vehicles: you meet lots of new people ("hey, what's this?"), you can transport nearly everything you need on a regular basis and it's better than a car if you live in a city like me (no parking fees, no searching for space to park a car, no insurances, taxes, gasoline, healthier & better for the environment,...). so go on and build your own, it's not that hard ;-)

(sorry no pic) i got myself two donor frames from the local dump: an old 26'' mountainbike (hardtail) and a 20'' kids bike. the kids bike is just needed for the front fork and wheel, so if you find one where everything else is rusty and broken - take it! the other bike is used as a whole.

after disassembling the bikes completely i took the bigger one and welded two tubes (construction steel, 34x2mm) to it as shown in the picture.

now it's time to decide how long your bike should be. after that i suggest to draw the front construction 1:1 on some paper and put the rear part beneath it. it helps a lot to see if everything fits together. after that use it to weld the pieces together.
some technical notes:
- be careful to have the main tube to the front parallel to the ground. this means to measure exactly as possible the dimensions of the front wheel and fork and the center of the back wheel (see drawing)
- for the steering angle of the front wheel i used 75°

take the fork from the bigger donor bike and cut it in three pieces as shown above. then weld the top two pieces to another steel tube (something that fits inside the head tube (by the way, a good source to learn bikeframe vocabulary is here: http://aarline.info/hotaar/wp-content/uploads/2011/09/BicycleTypogram_mini_Black2.png )) and extend the bottom with a piece of steel.

add a piece of metal to the fork in an angle of 90° as shown in the pic. a better position would be to move it more to the top (see annotation). that gives the wheel more space in left turns.
be careful to have the same distance from wheel center to the hole for the steering axis and from he center of the head tube to the hole for the steering axis. if these are different turning the handlebar doesn't result in the same turning of the front wheel.

the steering axis is screwed to some ball joints and connected to the two holes where it should rest. added is also some support to the bottom tube (see pic).

everything is disassembled and all metal parts are cleaned from rust and old paint. what you also see in this picture is the support for the load-box, made of steel tube and welded to the frame. the stand in the background is also made of small steel tube and was a pain to construct. next time i will try some motorbike kickstands, maybe that works out, too.

it's done!